1. Field of the Invention
The present invention relates to a synchromesh gear for a speed-change gear drive including a conically-shaped friction surface in the form of sharp-edged teeth each supporting a friction surface, which are separated from each other by oil evacuating grooves, and which is adapted for frictional mating engagement with a smooth opposite or counter cone.
2. Discussion of the Prior Art
A synchromesh gear of this type has already become known from U.S. Pat. No. 3,034,383. In this known synchromesh gear, an inner cone is interrupted by oil evacuating grooving or flutes which are uniformly distributed over the entire periphery and which extend in the direction of the generatrix of the cone and, in this manner, the cone is provided with an internal toothing. The surfaces of the teeth forming the inner cone are herewith constructed as friction surfaces and effect the friction engagement with the smooth opposite cone. Concurrently, the teeth are imparted the task, at the commencement of the snychromeshing sequence, of breaking the lubricating oil film which is present on the opposite cone whereby the oil will collect in the oil evacuating grooves and be removed therethrough as rapidly as possiblw from the region of the opposite cone which is necessary for the synchromeshing.
For the same purpose there is also known from German Published Pat. No. 1,911,409 a synchromesh gear which is constituted of a sintered material wherein, in a similar manner, the teeth are arranged to extend in an axial direction.
These known synchromesh gears, in contrast with similarly known synchromesh gears which are provided with threaded grooves, possess the advantage of being simpler to manufacture as well as being more wear-resistant. Nevertheless, the known synchromesh gears are commonly subject to the disadvantage that the removal of the lubricating oil film from the surface of the opposite or counter cone extends over a relatively lengthy period of time. The result thereof is a detrimentally long slippage movement between the friction surface and the opposite cone which will lead to a delay of the synchromeshing sequence, as well as to increased amount of wear.